Heat exchangers with flow distributing orifice partitions

ABSTRACT

A heat exchanger which is particularly useful as an evaporator has a first plurality of stacked plate pairs with cooling fins therebetween. A second plurality of stacked plate pairs is located adjacent to the first. Each plurality of plate pairs has enlarged plate end portions which together define flow manifolds. The first plate pairs have a first inlet manifold and a first outlet manifold. The second plate pairs have a second inlet manifold and second outlet manifold. The first outlet manifold is joined to communicate with the second outlet manifold. The second inlet manifold is joined to communicate with the first inlet manifold, but a barrier is located between the first and second inlet manifolds. The barrier has an orifice to permit a portion only of the flow in the first inlet manifold to pass into the second inlet manifold to produce a more uniform flow distribution inside the heat exchanger.

BACKGROUND OF THE INVENTION

[0001] This invention relates to heat exchangers, and in particular, toheat exchangers involving gas/liquid, two-phase flow, such as inevaporators or condensers.

[0002] In heat exchangers involving two-phase, gas/liquid fluids, flowdistribution inside the heat exchanger is a major problem when thetwo-phase flow passes through multiple channels which are all connectedto common inlet and outlet manifolds, the gas and liquid have a tendencyto flow through different channels at different rates due to thedifferential momentum and the changes in flow direction inside the heatexchanger. This causes uneven flow distribution for both the gas and theliquid, and this in turn directly affects the heat transfer performance,especially in the area close to the outlet where the liquid massproportion is usually quite low. Any maldistribution of the liquidresults in dry-out zones or hot zones. Also, if the liquid-rich areas orchannels cannot evaporate all of the liquid, some of the liquid can exitfrom the heat exchanger. This often has deleterious effects on thesystem in which the heat exchanger is used. For example, in arefrigerant evaporator system, liquid exiting from the evaporator causesthe flow control or expansion valve to close reducing the refrigerantmass flow. This reduces the total heat transfer of the evaporator.

[0003] In conventional designs for evaporators and condensers, thetwo-phase flow enters the inlet manifold in a direction usuallyperpendicular to the main heat transfer channels. Because the gas hasmuch lower momentum, it is easier for it to change direction and passthrough the first few channels, but the liquid tends to keep travellingto the end of the manifold due to its higher momentum. As a result, thelast few channels usually have much higher liquid flow rates and lowergas flow rates than the first one. Several methods have been tried inthe past to even out the flow distribution in evaporators. One of theseis the use of an apertured inlet manifold as shown in U.S. Pat. No.3,976,128 issued to Patel et al. Another approach is to divide theevaporator up into zones or smaller groupings of the flow channelsconnected together in series, such as is shown in U.S. Pat. No.4,274,482 issued to Noriaki Sonoda. While these approaches tend to helpa bit, the flow distribution is still not ideal and inefficient hotzones still result.

SUMMARY OF THE INVENTION

[0004] In the present invention, barriers or partitions are used in theinlet manifold to divide the heat exchanger into sections. The barriershave orifices to allow a predetermined proportion of the flow to passthrough to subsequent sections, so that the flow in the sequentialsections is maintained in parallel and more evenly distributed.

[0005] According to the invention, there is provided a heat exchangercomprising a first plurality of stacked, tube-like members havingrespective inlet and outlet distal end portions defining respective ofinlet and outlet openings. All of the inlet openings are joined togetherso that the inlet distal end portions form a first inlet manifold, andall of the outlet openings are joined together so that the outlet distalend portions form a first outlet manifold. A second plurality ofstacked, tube-like members is located adjacent to the first plurality oftube-like members. The second plurality of tube-like members also hasinlet and outlet distal end portions defining respective inlet andoutlet openings. All of the inlet openings are joined together so thatthe inlet distal end portions form a second inlet manifold and all ofthe outlet openings are joined together so that the outlet distal endportions form a second outlet manifolds. The second outlet manifold isjoined to communicate with the first outlet manifold. The second inletmanifold is joined to communicate with the first inlet manifold. Abarrier is located between the first and second inlet manifolds. Thebarrier defines an orifice to permit the portion only of the flow in thefirst inlet manifold to pass into the second inlet manifold.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Preferred embodiments of the invention will now be described, byway of example, with reference to the accompanying drawings, in which:

[0007]FIG. 1 is an elevational view of a preferred embodiment of a heatexchanger according to the present invention;

[0008]FIG. 2 is a top or plan view of the heat exchanger shown in FIG.1;

[0009]FIG. 3 is a left end view of the heat exchanger shown in FIG. 1;

[0010]FIG. 4 is an enlarged elevational view of one of the main coreplates used to make the heat exchanger of FIG. 1;

[0011]FIG. 5 is a left side or edge view of the plate shown in FIG. 4;

[0012]FIG. 6 is an enlarged sectional view taken along lines 6-6 of FIG.4;

[0013]FIG. 7 is a plan view of one type of barrier or partition shimplate used in the heat exchanger shown in FIGS. 1 to 3;

[0014]FIG. 8 is an enlarged sectional view taken along lines 8-8 of FIG.7;

[0015]FIG. 9 is a left end view of the barrier plate shown in FIG. 7;

[0016]FIG. 10 is a front or elevational view of the barrier plate shownin FIG. 7;

[0017]FIG. 11 is a plan view, similar to FIG. 7, but showing anothertype of barrier or partition plate used in the heat exchanger of FIGS. 1to 3;

[0018]FIG. 12 is plan view, similar to FIGS. 7 and 11, but showing yetanother type of barrier or partition plate used in the heat exchanger ofFIGS. 1 to 3;

[0019]FIG. 13 is an elevational view, similar to FIG. 4, but showinganother type of core plate used in the heat exchanger of FIGS. 1 to 3;

[0020]FIG. 14 is an elevational view similar to FIGS. 4 and 13, butshowing yet another type of core plate used in the heat exchanger ofFIGS. 1 to 3;

[0021]FIG. 15 is an enlarged sectional view taken along lines 15-15 ofFIG. 14;

[0022]FIG. 16 is an elevational view similar to FIGS. 4, 13 and 14, butshowing yet another type of core plate used in the heat exchanger ofFIGS. 1 to

[0023]FIG. 17 is an enlarged scrap view of the area indicated by circle5 in FIG. 16, but showing a modification to the location of the orifice;

[0024]FIG. 18 is a scrap view similar to FIGS. 17 but showing yetanother modification to the flow orifice;

[0025]FIG. 19 is a scrap view similar to FIG. 17 and 18 but showing yetanother modification to the flow orifice;

[0026]FIG. 20 is a scrap view similar to FIGS. 17 to 19 but showing yetanother modification to the flow orifice;

[0027]FIG. 21 is a diagrammatic perspective view taken from the frontand from the right side showing the flow path inside the heat exchangerof FIGS. 1 to 3;

[0028]FIG. 22 is a perspective view similar to FIG. 21, but taken fromthe rear and from the left side of the heat exchanger of FIGS. 1 to 3;

[0029]FIG. 23 is a perspective view similar to FIGS. 21 and 22, butillustrating the flow path in another pre,erred embodiment of thepresent invention;

[0030]FIG. 24 is a scrap view similar to FIG. 17, but showing a portionof one of the core plates that is used in the embodiment of FIG. 23;

[0031]FIG. 25 is a scrap view similar to FIG. 24 but showing a modifiedtype of orifice;

[0032]FIG. 26 is a scrap view similar to FIGS. 24 and 25, but showingyet another modification to the orifice;

[0033]FIG. 27 is a scrap view similar to FIGS. 24 to 26, but showing yetanother modification to the orifice; and

[0034]FIG. 28 is an elevational view of a core plate that is used inanother preferred embodiment of the invention where the inlet and outletmanifolds are located at opposed ends of the core plate, rather thanbeing adjacent as in the embodiments shown in FIGS. 1 to 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0035] Referring firstly to FIGS. 1 to 6, a preferred embodiment of thepresent invention is made up of a plurality of plate pairs 20 formed ofback-to-back plates 14 of the type shown in FIGS. 4 to 6. These arestacked, tube-like members having enlarged distal end portions or bosses22, 26 having inlet 24 and outlet 30 openings, so that the flow travelsin a U-shaped path through the plate pairs 20. Each plate 14 preferablyincludes a plurality of evenly spaced dimples 6 projecting into the flowchannel created by each plate pair 20. Preferably, fins 8 are locatedbetween adjacent plate pairs. The bosses 22 on one side of the plate arejoined together to form an inlet manifold 32 and the bosses 26 on theother side of the plates are joined together to form an outlet manifold34. As seen best in FIG. 2, a longitudinal tube 1-5 passes into theinlet manifold openings 24 in the plates to deliver the incoming fluid,such as a two-phase, gas/liquid mixture of refrigerant, to the righthand section of the heat exchanger 10. FIG. 3 shows end plate 35 with anend fitting 37 having openings 39, 41 in communication with the inletmanifold 32 and outlet manifold 34, respectively.

[0036] The heat exchanger 10 is divided into plate pair sections A, B,C, D, E by placing barrier or partition plates 7, 11, 12, such as areshown in FIGS. 7 to 12, between selected plate pairs in the heatexchanger. The inlet and outlet manifolds formed in the plate pairs ofeach section may be considered separate manifolds from each other, theinlet manifolds of adjacent sections being joined to communicate withone another and the outlet manifolds of adjacent sections being joinedto communicate with one another. For example the inlet manifold 32 ofsection C is joined to communicate with the inlet manifold of section Dand the outlet manifold of section C is joined to communicate with theoutlet manifold of section D. Referring to FIGS. 21 and 22, sections areshown schematically, and the dividing walls represent actual barrierplates 7, 11, and 12 as shown in FIGS. 7, 11 and 12. As shown in FIGS. 7to 12, each barrier may have an end flange or flanges 42 positioned suchthat the barrier plates can be distinguished from one another whenpositioned in the heat exchanger. For example barrier plate 7 has twoend flanges 42, barrier plate 11 has a lower positioned end flange 42and barrier plate 12 has an upper positioned end flange 42. Thedirection of flow is indicated with arrows. Referring again to FIGS. 21and 22, an inlet tube 15 delivers the fluid through an inlet 18 to theright hand section A of the heat exchanger where it would travel downalong the back, or along the right hand side of the plates 14 as seen inFIG. 4, cross over and travel up the front, or along the left hand sideof the plates as seen in FIG. 4. Barrier plates 7, 12 each include anopening 70 to accommodate the inlet tube 15. The flow then passesthrough a left hand hole 36 of barrier 7, traveling down along the fontof the next section B of plates, across and up the back of these platesto pass through a hole 38 in barrier plate 11 (see FIG. 11) whichsurrounds tube 15.

[0037] Most of the flow then travels down the backside add up the frontof the next section C of the heat exchanger plates and passes out viathe outlet manifold through an outlet hole 40, which is the left handhole of the barrier plate 12 shown in FIG. 12 through to the outletmanifold of section D. However, some of the flow passes via the inletmanifold of section C through a small orifice 17 (see FIG. 12) and intothe inlet manifold of the next section D of core plates. In this nextsection D, flow again travels down the back and up the front and outthrough the outlet hole 40 in the next barrier 12. Again some of theflow goes through the inlet manifold through an orifice 17 into theinlet manifold of yet another section E of core plates. In this lastsection E of core plates, the flow goes down the back, up the front andfinally out of the heat exchanger outlet 58.

[0038] Referring again to FIG. 21, it will be appreciated that in thefirst two sections of core plates from the right A, B the fluid isflowing in series through these sections. However, when the fluidreaches the third section C, most of it travels in the U-shapeddirection, but some of it is passed via the inlet manifold through thesmall orifices 17 in plates 12, to the next section's inlet manifold sothat the flow in the last three sections of core plates is in parallel.This parallel flow produces proportional, even flow distribution tobalance the flow rate among all of the sections in the heat exchanger.

[0039] Rather than using the core plates of FIG. 4 and the barrier orpartition plates of FIGS. 7 to 12, the partitions of FIGS. 7 to 12 couldactually be built right in or made an integral part of the core plates50, 52, 54 as shown in FIGS. 13 to 16. Core plate 50 as shown in FIG. 13is equivalent to core plate 14 of FIG. 4 with a barrier plate 7 of FIG.7 in that it has outlet opening 30 but inlet opening 24 includes anintegral barrier 60 with a hole 70 therethrough to accomodate tube 15Core plate 52 of FIG. 14 is equivalent to core plate 14 of FIG. 4 with abarrier plate 11 of FIG. 11 in that outlet opening 30 is blocked by anintegral barrier 62 and inlet opening 24 is not blocked. Core plate 54of FIG. 16 is equivalent to core plate 14 of FIG. 4 with a barrier orpartition plate 12 of FIG. 12 in that inlet opening 24 is blocked by anintegral barrier 64 having a hole 70 to accommodate tube 15 and anorifice 17 thereby allowing a portion of flow to pass through the inletmanifold to the next section. It will be appreciated that the coreplates of FIG. 13 and FIG. 14 would be used in the FIG. 21 embodiment inthe location of the respective partitions 7 and 11. The core plate shownin FIG. 16 would be used where the partitions 12 are indicated in FIG.21.

[0040] FIGS. 17 to 20 show different configurations of orifices 17 incore plates that would be used in the location of barriers 12 in theembodiment of FIG. 21. The different orifices 17 are used to balance theflow rates amongst all of the sections in the manifold. The flow ratescan be controlled by adjusting the sizes or locations (top or bottom) orthe shapes of the orifices, such as round, vertical slot, horizontalslot or any other configuration. The location of the orifice high or lowon the partition or core plate can be used to adjust the proportion ofliquid to gas phase within the flow that is passed through the orifice,while the size of the hole is used more to adjust the overall mass flowrate. The sensitivities of the orifice size and location will tend to beapplication-specific, depending on how well mixed the two phases of theflow are at the point of flow splitting. Also, rather than one orificehole, several smaller holes would be used. Further, the orifice in thefirst partition plate could be larger, or there could be more orifices,than in the second or down stream partition or barrier.

[0041] In the embodiment represented by FIG. 23, it will be noted thatthere is no longitudinal inlet tube. The flow as indicated with arrowsenters the left side of the heat exchanger, travels in series throughthe first two sections, and then in parallel through the last threesections in a manner similar to that of the embodiment of FIGS. 21 and22. In this FIG. 23 embodiment, it will also be noted that the inlet 18and outlet 58 are at opposite ends of the heat exchanger, rather thanbeing adjacent as in the embodiment of FIGS. 21 and 22. In theembodiment of FIG. 23, the core plates would not have holes toaccommodate a longitudinal inlet tube, as indicated in FIGS. 24 to 27.Similar modifications will be made to the barrier or partition plates 7,11, 12 of FIGS. 7 and 12, if such barriers are used with the core plates14 of FIG. 4 to make a heat exchanger as indicated in FIG. 23.

[0042] As mentioned above, the flow through the core plates travels in aU-shaped path in the embodiments of FIGS. 1 to 27. However, thisU-shaped path could be, in effect, straightened out, in which case coreplates 56 as shown in FIG. 28 would be used.

[0043] As will be apparent to those skilled in the art in the light ofthe foregoing disclosure, many alterations and modifications arepossible in the practice of this invention without departing from thespirit or scope thereof. The foregoing description is of the preferredembodiments and is by way of example only, and is not to limit the scopeof the invention.

1. A heat exchanger comprising: a first plurality of stacked, tube-likemembers having respective inlet and outlet distal end portions definingrespective inlet and outlet openings, all of said inlet openings beingjoined together so that the inlet distal end portions form a first inletmanifold and all of said outlet openings being joined together so thatthe outlet distal end portions form a first outlet manifold; a secondplurality of stacked, tube-like members located adjacent to said firstplurality of tube-like members, the second plurality of tube-likemembers also having inlet and outlet distal end portions definingrespective inlet and outlet openings, all of said inlet openings beingjoined together so that the inlet distal end portions form a secondinlet manifold and all of said outlet openings being joined together sothat the outlet distal end portions form a second outlet manifold; thesecond outlet manifold being joined to communicate with the first outletmanifold; the second inlet manifold being joined to communicate with thefirst inlet manifold; and a first barrier located between the first andsecond inlet manifolds, the barrier defining a first orifice to permit aportion only of the flow in the first inlet manifold to pass into thesecond inlet manifold.
 2. A heat exchanger as claimed in claim 1 whereinsaid barrier is a discreet baffle plate insert.
 3. A heat exchanger asclaimed in claim 1 wherein said barrier is integrally formed in one ofthe adjacent distal end portions of the first and second inletmanifolds.
 4. A heat exchanger as claimed in claim 1 wherein saidportion of the flow is small enough that it does not materially affectthe flow velocity through the first plurality of stacked tube-likemembers.
 5. A heat exchanger as claimed in claim 1 and furthercomprising: a third plurality of stacked, tube-like members locatedadjacent to said second plurality of tube-like members, the thirdplurality of tube-like members also having inlet and outlet distal endportions defining respective inlet and outlet openings, all of saidinlet openings being joined together so that the inlet distal endportions form a third inlet manifold and all of said outlet openingsbeing joined together so that the outlet distal end portions form athird outlet manifold; the third outlet manifold being joined tocommunicate with the second outlet manifold; the third inlet manifoldbeing joined to communicate with the second inlet manifold; and a secondbarrier located between the second and third inlet manifolds, thebarrier defining a second orifice to permit a portion only of the flowin the second inlet manifold to pass into the third inlet manifold.
 6. Aheat exchanger as claimed in claim 5 where said first orifice is largerthan said second orifice.
 7. A heat exchanger as claimed in claim 1wherein said first barrier further defines at least one further orificewhich hotter permits a portion of the flow in the first inlet manifoldto pass into the second inlet manifold.
 8. A heat exchanger as claimedin claim 1 where said orifice is a horizontal slot.
 9. A heat exchangeras claimed in claim 1 where said orifice is a vertical slot.
 10. A heatexchanger as claimed in claim 1 wherein each said tube like member is aplate pair formed of back-to-back plates defining a flow channeltherebetween.